1. Field
Aspects of the present invention relate to a method of forming a polycrystalline silicon layer, a thin film transistor, an organic light emitting diode (OLED) display device having the same, and methods of fabricating the same, and more particularly, to a method of crystallizing an amorphous silicon layer using a metal catalyst by scratching a buffer layer, the amorphous silicon layer or a capping layer in a linear pattern to control a metal silicide, and thus control crystal growth of a polycrystalline silicon layer.
2. Description of the Related Art
In general, polysilicon layers, which are used for semiconductor layers for thin film transistors (TFTs), have various advantages such as high electric field effect mobility, adaptation to high speed operational circuits, and realization of complementary metal-oxide semiconductor (CMOS) circuits. Transistors using such polysilicon layers are mainly used for active devices of active matrix liquid crystal displays (AMLCDs) and switching devices and driving devices of organic light emitting diode display devices (OLED display devices).
Methods of crystallizing an amorphous silicon layer into a polycrystalline silicon layer include solid phase crystallization (SPC), excimer laser crystallization (ELC), metal-induced crystallization (MIC), and metal-induced lateral crystallization (MILC). Presently, the methods of crystallizing an amorphous silicon layer using a metal are being widely studied because they enable the amorphous silicon layer to be crystallized within a shorter time at a lower temperature than SPC. The crystallization methods using a metal include MIC, MILC, and super grain silicon (SGS) crystallization. However, in these methods using the metal catalysts, it is difficult to control a seed formed of a metal silicide involved with forming a crystal grain, and device characteristics of the TFT can be degraded due to contamination caused by the metal catalyst.